Bleaching stages of rhodopsin will be investigated in the intact retina. While these bleaching stages have been studied at low temperatures, where they are stable and can be isolated, their spectra and kinetic behavior has not yet been determined under physiological conditions. It has not been proved, for that matter, that they exist under these conditions. This study will use techniques of kinetic spectroscopy with apparatus capable of nanosecond time resolution to investigate the bleaching stages. The goals of the research are: 1. To establish the existence or non-existence of the bleaching stages of rhodopsin under physiological conditions. 2. To determine the spectra of the stages under our conditions. 3. To determine the kinetic behavior of the bleaching stages under these conditions.